In the NXT graphical programming environment, a source block (such as a
motor rotation sensor) and a sink block (such as a variable write)
connected by a wire can be in very different places in the program.
Which value will be used when the sink block using the information is
executed -- the value of the source block at the time that block was
executed, or the value of the source block at the time the sink block
asks for it?
Since the software won't let me run a wire backwards in time from a
source block to an earlier sink on the same thread of execution, I
suspect that we read the sensor only once when the sensor block is
executed, rather than repeatedly each time a block asks for input from
But if that's the case, what happens when a wire connects a sink block
on one thread, with a source block on a different thread, and the sink
is executed before the source?
- posted 15 years ago